UI and inventories aside I'm really enjoying the Captain Scarlett DLC.
The level design is very well done, seeing the bones of a gigantic long dead monstrous fish spread over a mountainside is a sight to behold. As is the huge ship perched on a cliff above Oasis.
Also the little touches like the fact that all the music has changed once you leave the main Oasis hub. For me it's well worth the money & not a cheap cash in.